Generally speaking, the shape of a cap varies according to use and function. Most of caps are composed of the crown that covers the head and the visor that cuts off the light from the sun. Some kind of cap, such as hunting cap, is equipped with the ear flaps to protect the ears in winter time. However, most of the caps are prepared for a simple function.
Speaking more in details;
Problems neglected in composing the caps so far are preparation of enough space up to the summit of crown for the convenient movement of head up and down and assurance of ventilation inside the cap, as well as protection of face, method of attaching the ear flap to increase the ear function and neck cover to protect the neck outside the cap. Among the cap makers, such problems have not been considered important so far.
The matter of head movement up and down inside the crown of cap is important to level up the status of ready-made cap, currently produced in a number of standard patterns, to that of a cap made to measurement. In an attempt to adjust standard size caps to the heads of varied sizes as if they are made to measurement, flexibility devices are provided at the back edge of cap, to attain the effect of free-size caps. On the assumption that the relative height of head following the size of head is proportionate to the size of edge, the relative height was thought adjustable by adjusting the size of edge. However, in producing the caps, the relative height of crown of cap is ready made in certain patterns while only the edges are made adjustable. Therefore at the actual use of cap, the problem of relative height becomes outstanding unexpectedly. Sometimes the edge of cap comes down to touch the wearer's ear, or sometimes it remains too high from the level of one's ear so that the cap might be blown away by the wind. To solve such shortcomings, the depth of cap should have a system of adjustment as the back edge of cap is equipped with the flexibility device. For this object, the summit of crown needs to be elastic to assure the space for head movement.
So far, the problems of ventilation and change of air have been underestimated, and a few number of little holes on the crown were not enough to satisfy the absolute quantity of air. Such underestimation came probably from the fact that the cap is easier to be taken off than the shoes are, though keeping the cap in one's hand is inconvenient. So, it is actual that taking hat off is difficult while taking shoes off is not so difficult. It is indeed inside the cap that the health principle of keeping head cool and feet warm is neglected. Therefore the entire cap should be remodeled to improve the volume of ventilation.
The neck cover was attached for protection of skin in the summer and for prevention of cold air in the winter. However, one stretch of thick cloth was stitched into the edge of cap without distinction of neck or ear cover while it was actually both for neck and ear. As it is unable to equip the back edge of cap with flexibility device, the result was the unpleasant feeling coming from tight contact of cap with the skin. Also, the up-lifted neck cover when not in use and the unusual thickness of edge due to the stitch-in of neck cover decreased the beauty point.
In consideration of those problems as mentioned so far, the author invented a top knot cap (headgear provided with ponytail) composed of the top knot function added to the existing cap and had it registered for a number of design rights and utility model rights.
However, there exist various problems, such as limitation in expressing the designs of cap by connecting the knot portion and in the degree of utilization, while the summit of top knot portion connected to the crown of cap was made to be bound or unfastened by the use of binding cord, showing the function of opening or closing the summit of cap.